Catalyst for metathesis of cycloolefins

ABSTRACT

There is disclosed a new process for ring-opening polymerization of cycloolefins by the use of a catalyst comprising (A) tungsten or molybdenum halides, (B) alkyl aluminum halides and (C) an alcohol which has a nitrile substituent. Also the catalyst is disclosed as useful in metathesis of olefins.

This is a division of application Ser. No. 456,913 filed Apr. 1, 1974now U.S. Pat. No. 3,945,986.

This invention is directed to a process for the ring-openingpolymerization of unsaturated alicyclic hydrocarbons. It is alsodirected to novel catalyst systems useful for this ring-openingpolymerization process. These catalyst systems are further useful forthe interconversion of acyclic olefins according to the method known asthe olefin metathesis reaction (also called the olefin dismutation orolefin disproportination reaction).

The olefin metathesis reaction is a unique bondreorganization processwhereby materials possessing carbon-to-carbon double bonds, undergo aredistribution of constituents as depicted in the following equation:

    2R.sub.1 CH = CHR.sub.2 ⃡ R.sub.1 CH = CHR.sub.1 + R.sub.2 CH = CHR.sub.2

The olefin metathesis reaction, being an equilibrium process,facilitates: (1) obtaining the olefins R₁ CH = CHR₁ and R₂ CH = CHR₂starting from R₁ CH = CHR₂ ; or alternatively, (2) obtaining the olefinR₁ CH = CHR₂ by starting from a mixture of olefins R₁ CH = CHR₁ and R₂CH = CHR₂.

Similarly, the ring-opening polymerization reaction of cycloolefins alsoinvolves the scission of the carbon-to-carbon double bonds in thecycloolefin ring. The alkylidene carbons are rejoined to other suchcarbons derived from other monomer units to form the linear unsaturatedpolymer chain. Thus, the ring-opening of cyclopentene, for instance,yields a repeat unit:

    [ CH -- CH.sub.2 -- CH.sub.2 -- CH.sub.2 -- CH ]

this repeat unit has also been expressed in the following equivalentforms:

    [ CH = CH -- CH.sub.2 -- CH.sub.2 -- CH.sub.2 ]

and

    [ CH.sub.2 -- CH = CH-- CH.sub.2 -- CH.sub.2 ].

more specifically, the novelty of the present invention relates to theuse of nitrile-substituted hydroxy compounds employed as catalystmodifiers for transition-metal/aluminum-alkyl halide catalyzedring-opening polymerizations. These modifiers can be used to producecatalyst systems which exhibit excellent activity as cycloolefinring-opening polymerization catalysts. As a result, it is possible touse short reaction times and mild polymerization temperatures.Furthermore, very low catalyst concentrations may be used with excellentresults. Thus, good yields of product can be obtained when the molarratio of transition metal:monomer is as low as 1:20,000 or less.

The process of this invention comprises the ring-opening polymerizationor copolymerization of at least one unsaturated alicyclic compoundselected from the group consisting of (1) unsaturated alicycliccompounds containing four or five carbon atoms and one double bond inthe ring, (2) non-conjugated, unsaturated alicyclic compounds containingat least seven carbon atoms in the ring and at least one double bond inthe ring, and (3) polycyclic olefins and diolefins by subjecting saidalicyclic compounds or mixture thereof to polymerization conditions inthe presence of a catalyst system comprising (A) a transition metal saltselected from the group consisting of tungsten halides and oxyhalidesand molybdenum halides and oxyhalides, (B) at least one compoundselected from the group consisting of dialkylaluminum halides,alkylaluminum sesquihalides and alkylaluminum dihalides and (C) at leastone hydroxy compound of the general formula ROH wherein R is selectedfrom the group consisting of alkyl and cycloalkyl and wherein R containsa nitrile-substituent, wherein the molar ratio of A:B:C lies within therange of 1:0.5-10:0.5-3.

The desired polymerization of alicyclic olefins results in linear,unsaturated polymers having repeating unit derived from the opening thering of the unsaturated alicyclic compounds. It is known that thecatalysts useful in this process facilitate the cleavage ofcarbon-to-carbon double bonds. The resulting halves of molecules,designated alkylidenes fragments, then recombine to give the new olefinproducts. The polymerization catalysts of this invention may be employedto prepare a wide variety of useful polymers having different propertiesdepending upon the particular monomer or combination of monomers chosento be polymerized, the particular catalyst combination employed and theparticular polymerization conditions employed. The linear, unsaturatedproducts resulting from the use of the polymerization catalysts of thisinvention can be employed in a variety of applications, for example,they may be employed to produce finished rubber articles such aspneumatic tires, molded goods and the like or these materials may beuseful in coatings, in adhesives or in the manufacture of articles suchas films and fibers.

Representative but not exhaustive of the unsaturated alicyclic monomersdescribed in (1) above are cyclobutene, 3-methylcyclobutane,cyclopentene and 4-methylcyclopentene. Representative of the monomersdescribed in (2) above are cyclodecene, cyclooctene, cyclododecane,1,5-cyclooctadiene, 1,9-cyclohexadecadiene, 1,5,9-cyclododecatriene,3-methylcyclooctene, 3-phenylcyclooctene, 1-methyl-1,5-cyclooctadiene,1-chloro-1,5-cyclooctadiene, 1,2-dimethyl-1,5-cyclooctadiene and thelike.

Representative polycyclic olefins and diolefins described in (3) aboveare 3,3'-bicyclopentene, ##STR1## 3,3'-bicyclooctene, ##STR2##bicyclo[4,3,0]nona-3,7-diene, ##STR3## dicyclopentadiene, norbornadiene,norbornene, 5-vinylnorbornene, 5-alkylnorbornene and tricyclo[8,2,1,0²,9]trideca5,11-diene. ##STR4##

Representative of the organometallic catalyst components in (B) aboveare diethylaluminum chloride, diisobutyl aluminumchloride,diethylaluminum fluoride, dipropylaluminum bromide, ethylaluminumsesquichloride, methylaluminum sesquibromide, butylaluminumsesquichloride, ethylaluminum dichloride, propylaluminum dichloride,isobutylaluminum dibromide and the like. Of these, it is usuallypreferred to employ organoaluminum chlorides.

Representative of the compounds useful as the (C) catalyst component ofthe present invention include β-hydroxypropionitrile (also known ashydracrylonitrile, β-hydroxy-α-methylpropionitrile,2-hydroxyclyclopentanecarbonitrile, 2-hydroxycyclohexanecarbonitrile,4-hydroxyvaleronitrile and the like.

Generally, it is preferred to use a nitrile-substituted hydroxy compoundwherein the nitrile group is situated on the carbon atoms adjacent tothe carbon atoms bearing the hydroxy group, as in the representativeexamples given above. On the other hand, when the nitrile group issituated on that carbon atom which bears the hydroxy group, as in thecyanohydrins of aldehydes and ketones, or when the nitrile group is moreremote from the hydroxy group, as in 4-hydroxyvaleronitrile,4-hydroxyvaleronitrile, the resulting catalyst combinations generallyexhibit a lesser degree of activity for the ring-opening polymerizationprocess, although many catalyst combinations involving modifiers such asthese nevertheless exhibit a significant level of activity.

Representative of the transition metal salts described in (A) aretungsten hexachloride, tungsten hexabromide, tungsten oxytetrachloride,tungsten oxytetrabromide, tungsten oxytetrafluoride, tungstenoxytetraiodide and the like.

The catalyst systems set forth above are prepared by mixing thecomponents by known techniques. Thus, the catalyst systems may beprepared by "preformed" or "in situ" techniques, or by a combination ofthese techniques. By the "preformed" method, the catalyst components aremixed together prior to exposure of any of these components to thealicyclic monomers to be polymerized. In the "in situ" method, thecatalyst components are added individually to the alicyclic monomers. Inthe handling and transfer of the catalyst components, it is oftenconvenient to utilize solutions of these components in suitable inertsolvents such as benzene, toluene, chlorobenzene, hexane, pentane,cyclopentane and the like.

The order of addition of the catalyst components to each other is ofinterest in the practice of this invention.

When the "in situ" method is employed, solely, it is much preferred toadd the B component last, but the particular addition of the A and Ccomponents is generally not critical. Combinations of "in situ" and"preformed" methods can also be used effectively. In this case, it isgenerally preferred to employ the B component according to the "in situ"method, while component A may be preformed with component C.

It has been found that when the "preformed" technique is employed withthe catalyst components A and C, some aging of the mixture of thecomponents is desirable. During this aging period, color changes areusually observed. This aging period may require only a few minutes, orit may take several hours. The aging process can be carried out atambient temperatures in the range of 20°-25° C, or it may be acceleratedby the use of moderately elevated temperatures in the range of 30°-100°C. It has also been found to be advantageous to remove some of thehydrogen chloride which is formed as a by product when the "preformed"method is used.

Known techniques may be used for removal of this hydrogen chloride.These techniques include the use of a stream of an inert gas which canbe bubbled through the catalyst solution, or the use of a vacuum, towithdraw vapors of hydrogen chloride.

The amount of catalyst employed in the practice of this invention mayrange over a wide concentration range. Of course, a catalytic amount ofthe catalyst must be employed but the optimum amount depends upon anumber of factors such as the temperature employed, the particularalicyclic monomers employed, the purity of the reaction conditionsemployed, the reaction time desired, and the like. Generally, it ispreferred to use at least about 0.01 parts by weight of the A componentper 100 parts by weight of the alicyclic monomer or mixture of monomers.

The operating conditions which are employed in the process of thisinvention may vary. The polymerization may be carried out in solution orin bulk. When solvents or diluents are employed, they should be chosenso as not to adversely affect the desired polymerization process.Representative examples of useful solvents are liquid aromatichydrocarbons such as benzene, toluene and chlorobenzene, aliphaticsaturated hydrocarbons such as pentane, hexane, petroleum ether anddecane, and alicyclic saturated hydrocarbons such as cyclopentane,cyclohexane, decalin and the like.

The amount of solvent is not critical and may vary from none up to asolvent/cycloolefin weight ratio of 50/1, but more convenient ratios areabout 80/20 weight ratios.

Temperature at which the polymerization can be carried out can be variedover a wide range. It is generally preferred to conduct thesepolymerizations under relatively mild reaction conditions over the rangeof about -20° C to about 100° C.

The polymerization times will vary and can range from less than a minuteto 24 hours or more depending upon the polymerization conditions and theextent of polymerization desired. Generally, however, a satisfactorypolymerization product is obtained in a matter of only a few minutes orhours.

The polymerization reaction may be carried out as a batch or as acontinuous process. In performing the polymerization of this invention,the introduction of the monomer, catalyst and solvent, when a solvent isemployed, can each be made to the reaction zone intermittently and/orcontinuously.

The practice of this invention is further illustrated by reference tothe following examples, which are intended to be representative ratherthan restrictive of the scope of this invention. All experiments wereconducted in an atmosphere of dry nitrogen.

EXAMPLE I

The preformed technique was employed to prepare solutions of WCl.sub. 6modified with the various hydroxy compounds designated in Table 1. Therequired amount of the hydroxy compound was added to an 0.5 molarsolution of WCl₁ ₆ in dry benzene and allowed to react for about 24hours at about 23° C. These solutions were then flushed with drynitrogen to expel free HCl prior to being used. Ethylaluminum dichloride(EADC) or diethylaluminum chloride (DEAC) were employed as 0.20 molarsolutions in benzene.

A series of ring-opening polymerizations were carried out usingsolutions of freshly distilled cyclopentene (CP) in benzene. Thesepremix solutions were further purified by being passed through a mixtureof silica gel and alumina before being charged to reaction bottles.Polymerizations were conducted with 40 ml. of premix in 4-oz. glassbottles at 0° C. All manipulations of changing premix and catalystcomponents were conducted under a nitrogen atmosphere. The order ofcatalyst addition to the polymerization bottles containing premix wastungsten-alcohol alcohol component, followed by the organoaluminumcomponent.

In each of the experiments shown in Table 1, 0.40 ml of the solution ofthe tungsten-alcohol component was employed, which corresponded to amolar ratio of cyclopentene/tungsten of about 5000/1. Polymerizationswere terminated with a small amount of isopropanol, and the resultantsolutions were dried under vacuum. Inherent viscosities were determinedin benzene at 30° C. The percent trans values were determined by amethod described in Journal of Polymer Science; Polymer Physics Edition;Volume 11, page 529 (1973) published by John Wiley and Sons, Inc.

Experiments 10 and 11 are comparison tests which show thatnitrile-substituted alcohols in which the nitrile is not situated on thecarbon adjacent to that bearing the hydroxy group are much lesseffective as cocatalysts. Experiments 12 and 13 are comparison testswhich show that when the nitrile-substituent is not substituted on thehydroxy compound, the effectiveness of the cocatalyst is notsignificantly increased.

                                      Table 1                                     __________________________________________________________________________                     Molar                 CP Polym                                                                             Per-    Per-                    Exp              Ratio,                                                                              EADC,   DEAC,   conc,                                                                            Time,                                                                             cent                                                                              Inh cent                                                                              Appear-             No.                                                                              ROH           ROH/WCl.sub.6                                                                       Moles×10.sup.5                                                                  Moles×10.sup.5                                                                  wt. %                                                                            Min.                                                                              Conv.                                                                             Visc.                                                                             Trans                                                                             ance                __________________________________________________________________________       1##STR5##     6     --      18.0    60 63.0                                                                              5.47                                                                              91  rubbery solid           2                                                                                2##STR6##     3     --      18.0    60 54.1                                                                              8.51                                                                              --  "                       3                                                                                2##STR7##     4     --      18.0    60 75.6                                                                              5.02                                                                              92  "                       4                                                                                3##STR8##     8     --      18.0    60 77.0                                                                              3.51                                                                              --  "                       5                                                                                2##STR9##     8     --      19.9    100                                                                              76.0                                                                              3.42                                                                              --  "                       6                                                                                1##STR10##    8     --      19.0    120                                                                              70.3                                                                              --  86  "                       7                2     12      --      19.0                                                                             70  53.5                                                                              --  86  "                   8                                                                                2##STR11##    --    6       19.8    60 17.3                                                                              7.60                                                                              --  "                       9  --            0     6       --      18.0                                                                             60  1.3 --  --  --                  10                                                                               1##STR12##    6     --      21.6    90 8.9 --  --  --                      11                                                                               2##STR13##    8     --      19.0    70 13.4                                                                              --  76  --                      12 CH.sub.3 CH.sub.2 OH                                                                        2     8       --      21.1                                                                             120 19.9                                                                              --  --  --                  13.sup.a                                                                         CH.sub.3 CH.sub.2 OH                                                                        2     6       --      17.7                                                                             60  17.7                                                                              --  --  --                  __________________________________________________________________________    .sup.a                                                                           CH.sub.3 CN was added to the WCl.sub.6 solution with the CH.sub.3            CH.sub.2 OH during the preforming step; molar ratio                          ##STR14##                                                                    .sup.b                                                                          2-hydroxycyclopentanenitrile used in 6 and 7.                           

EXAMPLE II

A polymerization was carried out in order to illustrate theeffectiveness of nitrile-substituted modifiers when very low amounts ofcatalyst are employed.

A polymerization was carried out similar to Experiment 2 in Example I,except that 0.20 ml of the tungsten catalyst solution was employedinstead of 0.40 ml. The molar ratio of CP/W was about 9,200/l. A yieldof 73.0 percent was obtained of a strong rubber solid having an inherentviscosity of 4.69.

EXAMPLE III

A polymerization of CP was conducted similar to Experiment 3 of ExampleI except that the in situ technique was employed to modify the WCl.sub.6. Thus, 0.40 ml of an 0.05 molar solution of WCl.sub. 6 in benzene wasintroduced into 40 ml of a 20.4 wt-% solution of CP in benzenecontaining 4×10.sup.⁻⁵ moles of β-hydroxypropionitrile, followed by 0.40ml of a 0.20 molar solution of EADC. The yield was 81.2 percent ofrubber polymer having an inherent viscosity of 2.30.

EXAMPLE IV

In the absence of solvent, 25 ml of purified cyclopentene waspolymerized at 23° C by the addition of 1.0 ml of a preformed solutionof WCl.sub. 6 and β-hydroxypropionitrile prepared as described forExperiment 1 in Example I, followed by the addition of 0.60 ml of an0.20 molar solution of EADC. The reaction was terminated after 120minutes. A yield of 91.5 percent was obtained of a rubbery solid havingan inherent viscosity of 3.24

While certain representative embodiments and details have been shown forthe purpose of illustrating the invention, it will be apparent to thoseskilled in this art that various changes and modifications may be madetherein without departing from the spirit or scope of the invention.

I claim:
 1. A methathesis catalyst composition comprised of (A) at leastone transition metal salt selected from the group consisting of tungstenhalides, tungsten oxyhalides, molybdenum halides and molybdenumoxyhalides, (B) at least one compound selected from the group consistingof dialkylaluminum halides, alkylaluminum sesquihalides andalkylaluminum dihalides, and (C) at least one compound of the generalformula ROH wherein R is selected from the group consisting of alkyl andcycloalkyl, and wherein R contains a nitrile substituent situated on thecarbon atom adjacent to that bearing the hydroxy group, and wherein themolar ratio of A:B:C lies within the range of 1:0.5-10:0.5-3.
 2. Ametathesis catalyst composition according to claim 1 wherein (A) isselected from the group consisting of WCl.sub. 6, WBr₆ and (C) isβ-hydroxypropionitrile or β-hydroxy-α-methylpropionitrile
 3. Thecomposition according to claim 2 wherein (A) is WCl.sub. 6.